JPH10337726A - Method and device for adjusting pressure-contact force of cutter in plastic granulation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the long life of a cutter rotating while being brought into contact with a die face of a plastic granulation device and the continuous manufacture of granulated products of good quality. SOLUTION: In a plastic granulation device in which a sleeve 3 movable forward and backward is inserted into a fixed housing 2 and a cutter 23 installed on the end of a rotating shaft 5 journaled through a bearing 4 in the sleeve 3 is rotated while being brought into contact with a die face 25 and plastic discharged out of the die face 25 is cut to manufacture granulated products, a pressure sensor 21 is attached on a site for sensing the counterforce from the cutter 23 being brought into contact with the die face 25, and the rotating shaft 5 is moved forward and backward in compliance with the output of the pressure sensor 21 to keep the contact force of the cutter 23 to the die face 25 almost constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic granulating apparatus, in which a rotating shaft for realizing a longer life of a cutter which rotates while being pressed against a die surface and a continuous production of a high-quality granulated product are provided. The present invention relates to a method and an apparatus for adjusting a cutter pressing force for maintaining the cutter pressing force against a die surface at an appropriate value by moving the cutter forward or backward.

[0002]

2. Description of the Related Art In a conventional plastic granulating apparatus in which a rotary shaft is moved forward or backward by applying a forward pressure or a backward pressure by a pressure medium (oil or air), the pressing force of a cutter against a die surface is determined by: Water pressure in the box (a water flow is provided near the die surface and the cutter to cool the rotating cutter while pressing against the die surface), (2) the force applied to the rotating shaft by the sum of all pressure media, (3 ) Propulsive force of rotating cutter (the cutter blade is inclined with respect to the rotation axis, so a force is generated in the direction of the rotation axis like a so-called propeller), (4) the discharge pressure of plastic from the die surface, etc. Was estimated from. In other words, the pressing force is adjusted by the operator while guessing from the control parameters (1) to (4) so that the pressing force estimated as described above becomes an appropriate value.

[0003]

If the pressing force of the cutter against the die surface remains at an appropriate value, the above-mentioned control parameters can be determined at the start of operation of the apparatus to continuously produce a high-quality granulated product. However, in actuality, (a) the wear of the cutter, and (b) the pressing force fluctuates when an unexpected external force is applied to the rotating shaft or the cutter, the granulated product becomes defective or the cutter may be damaged. Or For example, excessive pressing force causes abnormal wear of the cutter, shortens the life of the cutter, and causes breakage. In addition, if the pressing force is less than the appropriate value, the discharged plastic sneaks between the die surface and the cutter, resulting in a defect that the granulated product is not completely separated, and the plastic remaining on the die surface remains. There is also a risk of damaging the cutter. For this reason, conventionally, the operation of the device was stopped because the operation status of the device was conventionally stopped every time when the operation status of the device was observed and abnormalities that could be visually or audibly recognized (such as defective granulated products or breakage of the cutter) were discovered. The rate was low.

[0004] The decrease in the operation rate of the apparatus requires a lot of labor for the maintenance of the apparatus, not only increases the maintenance cost, but also takes time and effort to readjust the pressing force at the start of the restart of the apparatus. This has resulted in increased operating costs and, consequently, increased costs for granulated products. Therefore, in order to realize a longer life of the cutter blade that rotates while being pressed against the die surface in the plastic granulator and to continuously manufacture high-quality granulated products, the pressing force of the cutter against the die surface should be set to an appropriate value. It was decided to develop a method to keep and a device to realize this method.

[0005]

SUMMARY OF THE INVENTION As a result of the study, the present inventors have developed a cutter in which a sleeve that can move back and forth is inserted in a fixed housing, and a cutter is attached to the tip of a rotary shaft that is mounted in the sleeve via a bearing. Is rotated while pressing against the die surface, and it is possible to detect the reaction force from the cutter pressed against the die surface against the plastic granulator that separates the plastic discharged from this die surface to produce granulated products. A pressure sensor is attached to the part, and the rotating shaft is advanced or retracted according to the output of the pressure sensor, so that the cutter pressing force adjusting method in the plastic granulating apparatus that keeps the pressing force of the cutter against the die surface substantially constant. is there. The output of the pressure sensor is taken out as an electric signal corresponding to the external force, and the control device operates the drive device of the pressure medium for applying the forward pressure or the backward pressure to the sleeve based on the fluctuation of the electric signal, thereby moving the rotary shaft forward or backward. Is preferred.

This method is suitable for quickly responding to a relatively small fluctuation range, and is referred to as a fine adjustment method in the present invention. The slightly fluctuating pressing force usually appears as a longitudinal movement of the rotation axis relative to the sleeve. In the fine adjustment method, the forward pressure or the reverse pressure is increased or decreased, and the rotational axis is moved back and forth in the direction opposite to the direction of the fluctuation of the pressing force to suppress the amplitude of the fluctuation range of the pressing force, or is included in the fluctuation range. Close to the ideal crimping force. In addition to directly detecting the reaction force, the reaction force may be indirectly known by detecting the sum or difference between the force and the reaction force applied in advance to a specific portion of the plastic granulator. The rotating shaft is used as the part to directly detect the reaction force,
Bearings can be used to detect the sum or difference between the reaction force and another force. In addition, a detection member that moves back and forth in conjunction with the rotating shaft is provided to detect the reaction force. It may be.

In this fine adjustment method, a change in the pressing force is regarded as a change in a reaction force received by a cutter pressed against the die surface, and a portion where the reaction force can be detected, usually a rotary shaft or a pressure sensor attached to a bearing. The pressing force is kept substantially constant (appropriate value) by moving the rotating shaft forward or backward according to the output. In the adjustment of the pressing force during operation of the apparatus, the pressing force of the cutter can be adjusted within the range in which the sleeve moves back and forth by adjusting only the forward pressure, so that the retreat pressure can not be particularly controlled.

[0008] Further, for the plastic granulator,
A forward movement sensor for detecting the advance amount of the sleeve due to the wear of the cutter is attached to the sleeve, and the position of the stopper for setting the retreat limit position of the sleeve is set. Is also good. The position of the stopper can be set, for example, by a method in which an operator or a control device operates a driving device of the stopper to move the stopper when the advance sensor detects the advance of the sleeve by a predetermined amount or more. The retraction limit position refers to a position where the stopper is fixed to limit the retraction of the sleeve. The stopper indirectly restricts the retraction of the rotating shaft by restricting the retraction of the sleeve, and thus suppresses the fluctuation of the pressing force. Although it depends on the operating conditions of the plastic granulator, an appropriate restricted retreat position is usually set so that the sleeve is restricted from retreating by the stopper when retreating to or near the last retreat position in the fluctuation range of the rotating shaft. The above-described method of adjusting the pressing force is to reset the limit retreat position of the stopper again, and is referred to as a coarse adjustment method in contrast to the fine adjustment method.

Since the plastic granulating apparatus operates continuously for a long period of time, it compensates for a decrease in the pressing force due to long-term wear of the cutter and the like, and as a result, the rotary shaft and the sleeve move forward as a unit and little by little. This means that the position where the current stopper is fixed is shifted from the initially set appropriate limit retreat position.If the advance amount of the sleeve exceeds a certain value, the purpose of restricting the retreat of the sleeve is achieved. Therefore, it becomes necessary to reset the retreat limit position of the stopper. The coarse adjustment method knows the timing of resetting the retreat limit position from the detection amount of the forward sensor, and simultaneously moves the stopper forward by the detection amount to the same retreat limit position as before or to the proper retreat limit position after resetting. The stopper is moved forward to achieve an appropriate pressing force. As described above, the fine adjustment method deals with short-term fluctuations and minute fluctuations, and the coarse adjustment method deals with long-term fluctuations and large fluctuations. Since both have different purposes, they can be applied individually. However, when both are used together, the plastic granulator can be operated automatically for a long period of time, and when the advance of the stopper exceeds the appropriate retreat limit position, the pressing force adjustment of the fine adjustment method works, and mutual A further preferred embodiment can be established because of the added benefit of working with complementary relationships.

The position of the stopper is set for the purpose of restricting the retreat of the sleeve. Normally, the stopper restricts the retreat of the sleeve when the stopper retreats to the last retreat position or in the vicinity thereof in the fluctuation range of the rotating shaft. Set the appropriate limit position to. The position of this stopper can be set before the last retreat position. That is, when the position of the stopper is set between the fluctuation center position of the sleeve and the last retreat position, the cutter comes into pressure contact with the die surface from beginning to end, and is particularly difficult to cut. Applied to Furthermore,
The position of the stopper can be set between the fluctuation center position of the sleeve and the most advanced position, and is particularly applied to a case where the user wants to operate while sharpening the cutter blade.

In the fine adjustment method, a sleeve that can move back and forth is inserted into a fixed housing, and a cutter attached to the tip of a rotating shaft that is axially mounted via a bearing in the sleeve is rotated while being pressed against the die surface. In a plastic granulator having an elastic member disposed between the rear surface of the outer ring of the bearing and the sleeve, a pressure sensor disposed between the front surface of the outer ring and the sleeve, and a forward pressure or a reverse pressure applied to the sleeve. The present invention can be embodied as a cutter pressing force adjusting device including a driving device for the pressure medium to be applied and a control device for operating the driving device according to the output of the pressure sensor. Since the pressure contact force is relatively large, a load cell as a pressure detecting device can be typically used for the pressure sensor, but any existing pressure detecting device or element can be used as long as it can withstand high pressure. As the elastic member, a spring is generally used, but a rubber elastic body or the like having elasticity or repulsive force equivalent to the spring can also be used as described above.

The forward pressure or the backward pressure includes hydraulic pressure, hydraulic pressure, pneumatic pressure, etc. applied between the housing and the sleeve. The pressure for pushing the sleeve forward with respect to the housing is the forward pressure, and the pressure for pushing the sleeve backward is the same. It becomes retreat pressure. However, during operation of the device, the forward pressure and the retreat pressure are always applied to the sleeve, so by adjusting one of the forward pressure and the retreat pressure, the sleeve can be moved forward or backward according to the difference between the two. Since it is possible to perform automatic adjustment for a minute change in the pressing force, it is more practical to merely increase or decrease one of the forward pressure and the backward pressure, and the configuration of the apparatus is simplified. The retraction pressure is used to move the cutter away from the die surface after the device stops, and the pressure contact force tends to decrease over time, so actually the pressure contact force is automatically adjusted by adjusting the forward pressure. Is preferred. The forward pressure or the reverse pressure is preferably air pressure from the viewpoint of enhancing the reaction of automatic adjustment, and hydraulic pressure from the viewpoint of suppressing the compression of the pressure medium due to the fluctuation of the pressing force. Conventionally, there is a two-stage apparatus in which hydraulic pressure is used for forward pressure or retreat pressure (front stage) directly applied to the sleeve, and pressurization by air pressure (rear stage) is applied to the hydraulic pressure. It is preferable that the driving device adjusts the air pressure in the subsequent stage. The control device that receives the electric signal from the pressure sensor adjusts the pneumatic pressure corresponding to the forward pressure or the reverse pressure by the driving device according to the electric signal.

In the coarse adjustment method, a sleeve that can move back and forth is inserted into a fixed housing, and a cutter attached to the tip of a rotating shaft that is axially mounted via a bearing in the sleeve is rotated while being pressed against the die surface, In a plastic granulating apparatus for manufacturing a granulated product by separating a plastic discharged from a die surface, a cutter comprising a forward sensor for outputting a position of a sleeve with respect to a housing and a stopper for setting a retreat limit position of the sleeve. Can be embodied as a pressing force adjusting device. In this press-contact force adjusting device for a cutter, the position of the stopper may be formed by forming a worm gear in the rotation direction of the outer peripheral surface of the stopper screwed to the rear end of the housing, and being adjustable by a worm that meshes with the worm gear and rotates. . The combination of the worm gear and the worm reduces the advance amount of the stopper with respect to the operation amount, and enables fine adjustment. For example, the fine adjustment may be realized by using a reduction mechanism based on a combination of gears.

The advance sensor may be of any form and specification as long as it has the ability to notify the advance of the sleeve relative to the housing to the outside. For example, a pressure sensor is arranged on one of the housing and the sleeve at a portion sandwiched between the housing and the sleeve, and the amount of advance of the sleeve is detected from an electric signal output from the pressure sensor. The reference portion such as a needle attached to the sleeve moves relative to the scale, so that the amount of advance of the sleeve can be visually recognized by an operator.
For example, a dial gauge may be used. In the former case,
When the electrical signal exceeds a certain value, the control device can be activated to automatically rotate the worm, whereas the latter evaluates the amount of advance by the operator, and if necessary, manually or mechanically warms the worm. Is rotated.

As described above, the forward sensor is constituted by an electric element such as a pressure sensor, and when the electric signal output from the forward sensor exceeds a certain value, the control device automatically operates the worm to advance the stopper. This makes it easier to automate the device, but the resetting of the retraction limit position of the sleeve by advancement of the stopper is performed at regular intervals, unlike the above-described automatic adjustment by increasing or decreasing the forward pressure or the reverse pressure. To do so, manual work by workers with low equipment and operating costs is sufficient. In this case, it is preferable to use a dial gauge or the like that allows the operator to visually check the forward movement sensor. Since the amount of advance of the stopper is small relative to the amount of rotation of the worm, fine adjustment is possible, and there is no danger that the stopper will advance far beyond the appropriate limited retreat position even by manual operation. In addition, in a plastic granulating apparatus in which both the fine adjustment method and the coarse adjustment method are embodied, even if the stopper moves forward beyond an appropriate retreat limit position, the above-mentioned forward movement is caused by the fluctuation of the pressing force due to the advance of the stopper. There is an advantage that the pressure contact force is maintained at an appropriate value by automatic adjustment by adjusting the pressure or the retreat pressure.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings. FIG. 1 is a perspective sectional view in the direction of a rotation axis showing a main part of a general plastic granulating apparatus to which the method for adjusting a pressing force according to the present invention is applied, and FIG. 2 is an enlarged view of the vicinity of a bearing housing 1 in FIG. Indicates a state where the pressing force is at an appropriate value.

As shown in FIG. 1, the plastic granulator of this embodiment has a structure in which a sleeve 3 which can move back and forth is inserted into a fixed housing 2 and an inner ring 18 is held by outer rings 19 and 20. The rotating shaft 5 is supported in the sleeve 3 via a bearing (angular contact bearing 4). The retraction pressure 6 is a one-stage hydraulic configuration,
The forward pressure 7 has a two-stage configuration using hydraulic pressure at the front stage and air pressure at the rear stage. The sleeve 3 is retracted by hydraulic pressure applied to a retraction pressure chamber 9 provided between an intermediate ridge 8 provided on the inner surface of the housing 2 and a front outer surface of the bearing housing 1, and the housing rear ridge 10 and the bearing housing 1 is advanced by hydraulic pressure applied to a forward pressure chamber 11 provided between the rear pressure chamber 11 and the rear outer surface. To adjust the forward pressure 7 during operation of the apparatus, the air pressure is adjusted by a pump 13 operated by the control device 12 to control the hydraulic pressure applied to the forward pressure chamber 11. A stopper 14 which is screwed into the housing 2 and abuts on the rear end surface of the sleeve 3 has a worm gear in a rotating direction on the outer peripheral surface.
Worm that is engraved with 15 and meshes with worm gear 15
Operate 16 to move back and forth. The worm 16 is operated by an operator (not shown) by checking the value of the dial cage 17 attached to the sleeve 3 (displaying the displacement amount of the sleeve 3 with respect to the housing 2 and providing an integrated amount).

The angular contact bearing 4 is
As shown in FIG. 2, the inner ring 18 having a radially convex outer peripheral surface is held by the front and rear outer rings 19, 20.
The inner ring 18 can rotate at a high speed integrally with the rotation shaft 5 with respect to the rotation shaft 20. The inner ring 18 is attached to the rotating shaft 5 and rotates integrally. The outer rings 19 and 20 are brought into close contact with each other, and are pushed forward integrally by a spring 22 having the rear inner surface of the bearing housing 1 as a base, and the springs are loaded on a load cell 21 disposed between the front inner surface of the bearing housing 1 and the outer ring 19. A pressing force Psp of 22 is applied as preload. That is, the outer rings 19 and 20 are
It is dressed between 1 and the spring 22. Note that the outer rings 19 and 20 are not fixed to the sleeve, and are slightly displaced by being pressed by the inner ring 18 that is displaced integrally with the rotating shaft 5 that moves back and forth due to a change in the pressing force. At this time, if the friction between the outer rings 19 and 20 and the sleeve 3 is large, the output of the load cell 21 is affected. For example, a groove is formed in the contact surface of the outer ring with the sleeve, and lubricating oil or the like is poured to reduce the friction. Good.

Next, the function of the pressing force adjusting method of the present invention will be described according to the state of the pressing force. 3 is a diagram corresponding to FIG. 2 showing a state where the pressing force is increased, FIG. 4 is a diagram corresponding to FIG. 2 showing a state where the pressing force is reduced, and FIG. FIG. 3 is a diagram corresponding to FIG. 2, showing a state in which a stopper 14 is advanced in accordance with displacement of a shaft 5 forward.

In the general plastic granulating apparatus shown in the present embodiment, the sleeve 3, that is, the rotating shaft 5 is displaced forward by moving the stopper 14 forward from the stopped state, thereby bringing the apparatus into an operating state. The advance amount of the stopper 14 is determined from a retreat limit position set in advance so as to obtain a target pressure contact force, and the operator moves the stopper 14 forward by operating the worm based on the dial gauge 17. . Stopper
The pressure contact force can be adjusted by increasing or decreasing the retreat limit position 14; however, as shown in FIG. 2, by adjusting the forward pressure Pf (and, if necessary, the retreat pressure Pb), the appropriate pressure contact force PM can be obtained.
To achieve. As a result, the preload Psp of the spring is reduced by the pressing force PM (more precisely, the reaction force equivalent to the pressing force PM), and the load cell 21 receives the electric signal V proportional to (Psp-PM).
M will be output to the control device 12.

The cutter 23 is pushed by the plastic pressure discharged from the die surface 25 and the effect of the water pressure in the cutter box 24.
(See FIG. 1 above.) When the appropriate pressing force PM increases to an excessive pressing force PH, as shown in FIG. 3, the amount of attenuation by the pressing force PH with respect to the pressing force Psp of the spring 22 increases. Thus, the pressing force applied to the load cell 21 (Psp-PM)
Decreases to the pressing force (Psp-PH), and the electric signal VM output from the load cell 21 changes to the electric signal VH. Electric signal V
The control device 12 having received H recognizes the change in the electric signal as a change in the pressing force and returns the pressing force PH to the pressing force PM.
Activate the pump 13 to reduce the air pressure (-α), and the forward pressure 7
Is reduced to Pf-α, and the sleeve 3, that is, the rotating shaft 5 is retracted. The pressing force continuously decreases with the retreat of the rotating shaft 5, but the fluctuation of the pressing force decreases.
As a result of the feedback to 21, the pressure contact force gradually decreases, and the drive of the pump 13 by the control device 12 is stopped when the pressure pressure reaches an appropriate pressure force PM. As described above, the adjustment system of the pressing force by the load cell 21 constitutes a negative feedback control system. In this example, the air pressure is increased by the pump 13, but the pressure can be reduced without using the pump 13 if the air is released. In this case, for example, a mechanism that can adjust the open area of the valve so that the amount of reduced pressure can be continuously adjusted is preferable.

Contrary to the above, when the cutter 23 is worn or the discharge pressure of the plastic discharged from the die surface 25 decreases (see FIG. 1), and the pressing force PM decreases to the pressing force PL, as shown in FIG. The pressing force Psp of the spring 22 is
The amount of elimination due to the reaction force PL decreases. Thus,
The pressing force (Psp-PM) applied to the load cell 21 is equal to the pressing force (Psp-
PL), and the electric signal VM output by the load cell 21
Changes to an electric signal VL. The control device 12, which has received the electric signal VL, recognizes the change in the electric signal as a change in the pressing force and operates the pump 13 to increase the air pressure (+ α) in order to return the pressing force PL to the pressing force PM. By increasing the forward pressure 7 to Pf + α, the sleeve 3, that is, the rotating shaft 5 is advanced.
The pressing force continuously increases as the rotating shaft 5 advances,
As a result of the fluctuation of the increase in the press contact force being fed back to the load cell 21, the increase in the press contact force becomes gradually slower.
, The driving of the pump 13 is stopped.

When the wear of the cutter is further advanced, the sleeve is displaced forward by the forward pressure, and the restriction of the retreat of the sleeve by the stopper does not substantially function. There is a risk that plastic may enter between them. Therefore, in this example, the advance amount of the sleeve is displayed on the dial gauge 17, and when the value of the dial gauge 17 exceeds a certain value, the operator operates the worm to advance the stopper. As shown in FIG. 5, even if the stopper 14 has an appropriate pressing force PM when the stopper 14 is advanced, when the stopper 14 again comes into contact with the rear end face of the sleeve 3, the pressing force PM is temporarily reduced to the pressing force PH.
Or it changes to PL. The operator may stop the operation after confirming that the pressing force fluctuates due to the contact of the stopper 14 with the rear end surface of the sleeve 3 and the control device 12 has acted. In an apparatus using both the control system based on the fine adjustment method and the control system based on the coarse adjustment method as in this example, even if the new retreat limit position set by the forward stopper 14 is not accurate, the forward pressure 7 of the present invention is not affected. Alternatively, since the automatic adjustment function using the retreat pressure 6 works, there is an advantage that a proper pressure contact force PM can be achieved.

The adjustment of the pressing force using the forward pressure or the backward pressure is always necessary during the operation of the apparatus, but the resetting of the backward movement restricting position by the stopper is not always necessary. Therefore, a method of operating the stopper by the operator is most practical from the viewpoint of suppressing equipment or operation costs as in this example. Also, in this example, the example in which the pressure control by the fine adjustment method and the pressure control by the coarse adjustment method are used together is shown. However, both can be applied individually, and the fine adjustment can be performed particularly by omitting the control by the coarse adjustment method. It is possible to control the pressing force for a long time only by the control by the method (for example, to increase the forward pressure for a long time).

[0025] However, the fine adjustment method corresponds to a minute change in the pressing force, whereas the coarse adjustment method adjusts the pressing force in a form to prevent abnormal rotation of the rotating shaft due to a decrease in the pressing force. Therefore, it can be said that both purposes are originally different and complementary. For this reason, it is not realistic to omit the control by the coarse adjustment method. Rather, the control system for the fine adjustment method and the coarse adjustment method should be integrated, and further, in order to automate the advance of the stopper, instead of the dial gauge of the above-mentioned example, a forward sensor for monitoring the advance distance of the sleeve or the rotating shaft is used. It is preferable to output a signal and control the motor that rotates the worm via the control device.

[0026]

According to the present invention, since the pressing force of the cutter in the plastic granulating apparatus is properly maintained, the life of the cutter can be extended, and there is no danger of the cutter being broken except in unusual circumstances. . Since the effect of this cutter is not affected by the material of the cutter, it has the advantage of enabling the practical use of hard and brittle cutters such as TiC (titanium carbide). Since a situation in which the apparatus is stopped is avoided, it is possible to ensure stable and continuous operation of the apparatus. Further, from the viewpoint of the granulated product, the proper pressing force of the cutter prevents the generation of the unseparated granulated product, and enables the production of the granulated product having the best appearance. Thus, the present invention mass-produces high-quality plastic granulated products,
It contributes to providing it at low cost.

[Brief description of the drawings]

FIG. 1 is a perspective view in the rotation axis direction showing a main part of a plastic granulator to which the present invention is applied.

FIG. 2 is an enlarged view of the vicinity of a bearing housing portion in FIG. 1 in a state where a pressing force is appropriate.

FIG. 3 is a diagram corresponding to FIG. 2 in a state where the pressing force is increased.

FIG. 4 is a view corresponding to FIG. 2 in a state where the pressing force is reduced.

5 is a diagram corresponding to FIG. 2 in a state where the cutter is worn and the stopper is advanced.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bearing storage part 2 Housing 3 Sleeve 4 Angular contact bearing 5 Rotating shaft 6 Retraction pressure 7 Forward pressure 8 Intermediate convexity 9 Retraction pressure chamber 10 Housing rear convexity 11 Forward pressure chamber 12 Control device 13 Pump 14 Stopper 15 Worm gear 16 Warm 17 Dial gauge 18 Inner ring 19 Outer ring divided in front 20 Outer ring divided in back 21 Load cell 22 Spring 23 Cutter 24 Cutter box 25 Die surface

Claims (8)

[Claims] 1. A fixed housing is provided with a sleeve that can move back and forth, and a cutter attached to the tip of a rotating shaft that is axially mounted on the sleeve via a bearing is rotated while being pressed against the die surface. A pressure sensor is attached to a part capable of detecting a reaction force from a cutter pressed against a die surface with respect to a plastic granulating apparatus for manufacturing a granulated product by dividing plastic discharged from the apparatus, and an output of the pressure sensor. A pressing force of the cutter in the plastic granulating apparatus, wherein the pressing force of the cutter against the die surface is kept substantially constant by moving the rotating shaft forward or backward according to the following. 2. The method according to claim 1, wherein the portion capable of detecting a reaction force from the cutter pressed against the die surface is a rotary shaft or a bearing. 3. An output of the pressure sensor is an electric signal proportional to an external force, and a control device activates a driving device of a pressure medium for applying a forward pressure or a reverse pressure to the sleeve based on a fluctuation of the electric signal, and the control device operates the rotation shaft. 3. The method for adjusting the press-contact force of a cutter in a plastic granulating apparatus according to claim 1 or 2, wherein the cutter is moved forward or backward. 4. A fixed housing is provided with a sleeve which can be moved back and forth, and a cutter attached to a tip of a rotating shaft which is axially mounted on the sleeve via a bearing is rotated while being pressed against a die surface. For a plastic granulating apparatus for manufacturing a granulated product by dividing the plastic discharged from the apparatus, a forward sensor for detecting the advance amount of the sleeve is attached to the sleeve, and a stopper for setting a retreat limit position of the sleeve is provided. A method for adjusting a pressing force of a cutter in a plastic granulator, wherein a position is set. 5. A method for adjusting the pressing force of a cutter in a plastic granulating apparatus, wherein the method according to claim 1, 2 or 3 and the method according to claim 4 are used together. 6. A fixed housing is provided with a sleeve which can be moved back and forth, and a cutter attached to the tip of a rotating shaft axially mounted via a bearing in the sleeve is rotated while being pressed against a die surface. In a plastic granulator having an elastic member disposed between a rear surface of a bearing outer ring and a sleeve, a pressure sensor disposed between the front surface of the outer ring and the sleeve, and a pressure medium for applying forward pressure or retreat pressure to the sleeve And a controller for operating the driving device according to the output of the pressure sensor. 7. A sleeve that can move back and forth is inserted into a fixed housing, and a cutter attached to a tip of a rotating shaft that is axially mounted via a bearing in the sleeve is rotated while being pressed against a die surface, and the die surface is rotated. Plastic granulator for producing a granulated product by separating plastic discharged from a plastic granulator, comprising: a forward sensor for outputting a position of a sleeve with respect to a housing; and a stopper for setting a retreat limit position of the sleeve. Pressure adjusting device for cutters. 8. A worm gear is formed in the direction of rotation of the outer peripheral surface of the stopper screwed to the rear end of the housing, and the position of the stopper can be adjusted by a worm that meshes with the worm gear and rotates. Pressure adjusting device for cutters in plastic granulators.